There was a page of mini-games that were canceled before the release of the game called the Limbo Page. The creator did not publish a visible link to this page.
Gain access to Limbo Page
Add three addresses and change all the value to 144.
Go to the userdata folder C:\ProgramData\PopCap Games\PlantsVsZombies\userdata and rename game#_10 to game#_13 (# is the user number so look for game1_10 if user 1)
It is Survival: Endless on the roof during nighttime, also known as Night Roof. This can be played by renaming the saved file in the user data folder. There is no need to use a Cheat Engine.
Play Dr. Zomboss's Revenge until you have enough plants and Dr. Zomboss is about to attack. The conveyor belt should be full and you should have 10 seed slots, or the game will crash after renaming.
Go to userdata and rename game#_35 to game#_30. (# is the user number e.g. game1_35 if user 1)
Go to Whack a Zombie and hit Dr. Zomboss when he is about to attack. Earn 350-500 sun by hitting zombies.